The present invention relates to greases comprising methylfluoroalkylsiloxanes and solid thickeners containing fluorinated polymers which have excellent lubricating properties.
Greases incorporating certain fluorosilicone polymers are known in the art and several are commercially available. For instance, greases containing poly 3,3,3-trifluoropropylmethyl-siloxane thickened with polytetrafluoroethylene are commercially available from a variety of sources.
Greases containing fluorosilicones with more than 1 perfluorinated carbon atom are also known in the art. For instance, U.S. Pat. No. 3,061,545 teaches greases containing fluorosilicones having repeating units of the structure RCH.sub.2 CH.sub.2 R'SiO in which R is a perfluoroalkyl radical of 1 to 10 carbon atoms and R' is a monovalent hydrocarbon radical of less than 3 carbon atoms. This reference, however, does not teach fluorinated polymer thickeners.
Similarly, U.S. Pat. No. 3,642,626 describes a grease containing a fluorosilicone polymer thickened with a perfluoropropylene-tetrafluoroethylene copolymer. This reference, however, requires the addition of an antimony dialkyl dithiocarbamate.
The present inventors have now discovered that the greases claimed herein have unexpected lubricating and antiwear properties.